Hyperphosphatemia is a common complication of chronic kidney disease (CKD), and it is an important factor to cause secondary hyperparathyroidism, the changes of calcium and phosphorus deposition, the metabolic disorders of vitamin D, and renal osteodystrophy. It is closely related with coronary calcification, valvular calcification and other serious cardiovascular complications. In the recent years, studies showed that a new type phosphate binding agent, lanthanum formulation, can effectively reduce the serum phosphorus level without causing secondary damage to the bone and hypercalcemia, and is a relatively safe phosphate binding agent, especially suitable for treating the patients with hyperphosphatemia who undergo a long-term hemodialysis. In general, as relatively safe therapeutic agents for treating hyperphosphatemia, aluminum hydroxide gel, calcium carbonate hydrate, calcium acetate hydrate, lanthanum carbonate hydrate and sevelamer can be used.
In the pathological presentation of hyperphosphatemia in chronic renal insufficiency, sometimes iron deficiency anemia or metabolic acidosis will happen. In this case, the anemia will further worsen if aluminum hydroxide gel is given. In addition, China patent literature CN100398112C (application NO. 200610043267.4) disclosed a medicine for treating hyperphosphatemia and a preparation method therefore, including an agent made from pharmaceutical effective ingredient, polystyrene sulfonic lanthanum, and pharmaceutic adjuvant. However, polystyrene sulfonic lanthanum can absorb iron when it undergoes ion exchange through the human digestive tract, therefore inhibit the iron absorption by intestinal, reduce the iron concentration and white blood cell hematocrit value in the blood and tissue of dialysis patients, finally aggravate the iron deficiency anemia of the dialysis patients. Similarly, WO94/27621 disclosed a method of binding iron ion by using an amino group-containing polymer; however, if the amino group-containing polystyrene and acrylic acid resins are given in the same way, the phenomena of the iron deficiency anemia will present. China patent literature CN1102393C (application NO. 96193918.4) disclosed a medical composition comprising a chosen lanthanum carbonate hydrate; in addition, China patent literature CN102573807A (application NO. 201080041895.3) disclosed a method of treating hyperphosphatemia by ferric citrate formulation. However, the two methods mentioned above will have side effect of irritation on the gastrointestinal tract in patients with renal failure.